President Bush's plan to return humans to the moon as a steppingstone to Mars was applauded Wednesday by many scientists eager to unlock the geological and biological secrets of the Red Planet.
Some scientists said federal money would be better spent on robotic exploration. Many others are concerned how a planned shift of existing NASA funds might impact non-human space exploration, including the fate of the Hubble Space Telescope.
At a press conference at NASA Headquarters in Washington, Bush called for robotic lunar missions later in the decade and a return of astronauts there between 2015 and 2020, with one goal being "an extended human presence" on the lunar surface.
A human mission to Mars would take place at an unspecified time thereafter, Bush said, when the necessary technology is in place and financing allows.
"This sounds like a lot of fun," said Ken Edgett, a geologist at Malin Space Science Systems, which operates the camera on the orbiting Mars Global Surveyor. "But Mars is again way off in the future. I think there's going to be a lot of Mars-types that are going to be disappointed by it, that we can't just go right to Mars. But you do have to crawl before you can walk."
NASA's budget is $15.5 billion for 2004. That amounts to $86 billion over five years. Bush called for an additional $1 billion during that time. He also wants $11 billion to be reallocated, mostly from existing human spaceflight efforts, to support the new direction. Existing agency funding would be redirected gradually from the shuttle and space station programs which, together, consume about $5 billion a year.
NASA funding would remain less than 1 percent of the overall $2.2 trillion in federal spending.
"Human beings are headed into the cosmos," Bush said.
Robots vs. humans
For at least two decades, scientists will have to continue examining Mars through the eyes of robots. Bush lauded robotic efforts but said, "We need to see and examine and touch for ourselves."
While some experts argue human spaceflight is simply not cost-effective, geologists generally saw the president's extended timeframe as a reasonable approach to mounting an effective humans-to-Mars plan.
Automated probes have for decades searched for signs of Martian water, the key ingredient to life as we know it. Scientists suspect but have not confirmed that ancient Mars at times contained rivers of water, as well as lakes or oceans. Firm evidence, gathered by robots, would guide the first human explorers.
"Ultimately it will probably will require a human presence on Mars to get into the details of the ancient past on Mars," said Bob Craddock, science adviser to the under secretary for science at the Smithsonian Institution.
Robots are a valuable tool for exploration, all scientists agree, but Craddock and others think they are inferior to astronauts in terms of speed and in grasping what's been observed and judging what to do next.
NASA's Spirit rover on Mars will, over the course of its three-month mission, do "what an astronaut could do in a day," Craddock told Space.com. "The science return for putting a person on Mars is exponentially better than a robot."
Craddock was told the details of Bush's speech early Wednesday.
"It filled me with emotion," he said. "It's really a very rational plan for doing this. Before it was only a dream. Now we have an actual plan."
Craddock is concerned, though, that scientists back on Earth might not get enough funding to analyze the bounty of data that would result from geologists' investigation other worlds. Already, he said, NASA does not spend enough to help researchers paw through the data beamed back by Mars probes.
"They really need to start pouring more money into the research programs to analyze the data," Craddock said. "They've been very stingy with it."
Robert Park, a physicist at the University of Maryland and director of the Washington office of the American Physical Society, does not think Bush's plan makes scientific sense.
"Aside from grand adventure, he has not given any reasonable explanation as to why we're doing it. These are not specific reasons. They're kind of the 'vision' reasons, but there's nothing concrete there."
Park thinks the plan's lack of specifics will make it hard to persuade Congress to go along with the cost.
"If I were in charge — and there are many people who are glad that I'm not — the first thing I'd do is lay down an absolute rule that no human being set foot on Mars," Park said.
His hard rule would be motivated by science. If the goal of Mars research is to look for life, Park thinks it is wrongheaded to send living beings there to do the looking. "The human being is essentially a bagful of organisms," he points out. The risk of contamination is high, and might ruin any chance of knowing whether bugs found were Martian or terrestrial. For Park, this is elementary science.
"We don't stick our finger into a liquid to see what the temperature is, we put in a thermometer," he said.
Park estimates that robotic exploration costs about 1 percent of the price of sending humans.
The White House plan, detailed in internal documents, also mentions the possibility of sending humans to asteroids or moons of Jupiter. The president did not expand on these possibilities but did declare that the moon would be a way station for Martian excursions and trips to "places beyond."
Park contends that Mars is about the only place beyond the moon that humans can go. Other planets and moons, as well as asteroids, present problems with extreme temperatures and radiation, or in some cases crushing gravity. So, he said, it makes more sense to take whatever might eventually go into a manned Mars mission and put it toward robotic exploration of many targets in the solar system.
Park is a big fan of the Spirit rover on Mars.
"We've got a geologist on Mars right now, and he's doing a great job," Park said. "If we put a human there, he's locked in a spacesuit, he has no sense of touch. There's not much to hear on Mars. All he's really got is a sense of sight. And are better than any human eyes."
Other scientists think putting geologists on Mars makes sense on several levels.
"It's good for science, but it's good for this country in a lot of ways," said Rick Chappell, a 25-year NASA employee, veteran of a space shuttle flight, and now director of the Dyer Observatory at Vanderbilt University.
"The Bush initiative has great potential in exciting our future scientists and engineers, that is, our students, to make a choice of exploration as a career, which is something they haven't been doing enough recently," he said. Chappell's own choice to pursue science was heavily influenced by President Kennedy's to go to the moon, he said.
Since the end of the Apollo era, that direction and inspiration has been lost, many scientists and space analysts agree. Chappell asks freshmen science students what they hear their country saying to them about exploration.
"They look at me like I'm sort of nuts," he said.
Chappell would like to see more money devoted to exploration and quicker time frames for getting humans out there, but he understands there are other concerns. Going to the moon in preparation for getting to Mars is logical scientifically, inspirationally and because of the technology that will be developed in the process, he said.
The interim goal of exploring the moon more thoroughly offers its own scientific opportunities.
The moon has almost no weathering or geologic activity, so its rocks and dust are ancient.
Scientists say detailed exploration by humans could confirm that the moon was indeed carved from Earth when a Mars-sized shortly after its formation. Rocks booted from Earth to the moon, long ago by asteroid impacts, offer about Earth's early geology.
Evidence suggests there is water frozen in permanently shaded lunar craters, near the poles. It could be broken down into hydrogen, to fuel a rocket trip to Mars, and oxygen to support lunar visitors.
Some analysts say exploring the moon and developing the means to put people on Mars would help keep America at the forefront of technology.
"Realistically this seems quite well thought out," Chappell said of the overall vision the president presented.
Astronomers are concerned about the details of how Bush's plans will be funded.
Bush did not outline any major changes to the robotic portion of NASA's budget. An internal White House statement obtained by Space News and Space.com says NASA would remain committed to expenditures in aviation, education and Earth science.
"Robotic missions will serve as trailblazers" to putting humans on Mars, Bush said.
Congressional sources told Space News, however, that NASA officials have said the refocusing would affect science programs not related to the new vision. No specifics were given, but one source said, "The rate of growth for the science budget will be slowed down."
Funding for NASA space science — which includes robotic missions to the planets and the Hubble and Chandra space telescopes but not satellites studying the Earth — has jumped significantly in recent years after a decade of fairly flat spending. In 2000, space science received $2.2 billion, compared with $4 billion for 2004.
Kevin Marvel, an astronomer and spokesman for the American Astronomical Society, said the lack of details provided by the president left his colleagues anxious about whether space science funding would be cut or go flat.
Marvel is also concerned that Bush's call to devote the shuttles to building the space station and to retire the shuttle fleet in 2010 would eliminate any chance of servicing Hubble, either to extend its life or even possibly improve it. Past shuttle missions have repaired the orbiting observatory and even installed a new and better camera.
Ken Edgett, the geologist at Malin Space Science Systems, has been studying Mars intently for the past six years. He loves his work but is doomed to short-term frustration.
"Most of us look at those pictures and think, 'Geez, I just want to walk out there,'" Edgett said Wednesday.
He does not expect robots to resolve most of the mysteries of the Red Planet.
"The only way we're ever going to understand Mars and its history is to have people there doing the work," Edgett said in a telephone interview.
Mars presents a rich geologic record in layered rock, just like on Earth. It is complex and will take "hundreds of geologists a century of digging around to figure out what that history is," he said.
"We're just sort of seeing the books and reading the titles on their spines," Edgett said. "We need to crack open those books and read the pages."